Conventionally, a head-mounted display device is known as a form of a display device that displays information such as characters or an image.
The head-mounted display device can be roughly classified into an eyeglass style, a goggle style, a cap style, and the like, according to the form. Further, the head-mounted display device can also be roughly classified into a see-through type or a non-see-through type according to whether a user can see the outside world together with display information in his/her field of view, which is realized with the see-through one and not realized with the non-see-through one.
With respect to the see-through type head-mounted display device, various proposals have been made in terms of an improved usability for a user. For example, an information display device has been proposed in which a display mode of display information is switched according to the behavior of the user (see Patent Document 1 (Japanese Laid-open Patent Publication No. 2007-163634)). In this information display device, the display mode is switched between a brief display mode and a detailed display mode according to the behavior of the user, such as whether the user is walking, or whether the user is looking at display information, or whether the user is talking, so as to perform an information display suitable for the behavior of the user.